Explosion of Caesium in Water

When metal comes in contact with water an explosion takes place.

Scientific name: Cesium reacts with water producing hydrogen which catches fire and explodes.


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The reaction is very rough! There is a serious fire risk - a fire extinguisher should be ready. Use safety screen. There will be an explosion - keep a safe distance.

Wear lab gloves and eye protection goggles or a face shield.

Always follow general safety recommendations. Please note that conducting chemistry experiments you must comply with the relevant legal procedures in your country.

Reaction formula

2Cs + H2O → 2CsOH + H2 2H2 + O2 → 2H2O


  1. Caesium
  2. Water

Step-by-step instruction

WARNING! This experiment is dangerous! You should NOT perform this at home. ONLY carry out this experiment, if you are a trained chemist, and you understand local safety and legal requirements, which are required to perform such experiments

  1. Fill the trough about half full with water.
  2. Prepare a special device which will allow you to put the metal into the water keeping a safe distance. Hook the metal with device.
  3. Place a beaker with a small piece of cesium under oil into the liquid nitrogen.
  4. Put all the equipment under a safety screen.
  5. Move away.
  6. Lift a piece of cerium using the device and drop it into the water.
  7. The reaction proceeds with a bang.

Scientific background

Cesium is a very reactive alkaline metal with a pretty golden shine. When it comes in contact with water it reacts rapidly as follows:

2Cs + H2O → 2CsOH + H2

A lot of heat is produced in this reaction. It passes faster than the same reaction of other alkaline metals (except for francium) because the alkaline properties increase with size of atom. Hydrogen formed in the reaction catches fire and reacts with the oxygen of air making the explosion:

2H2 + O2 → 2H2O


Published on 11 March 2015

  • Fire
  • Heating with fire
  • Explosion
  • Poisoned gas
  • Organic
  • Electricity
  • Solution
  • Oxidation reduction
  • Color change
  • Precipitate
  • Gassing
  • Catalyst